Studies on shoot growth and bunch development as influenced by the time of pruning and hydrogen cyanamide application in Thompson Seedless grape (Vitis vinifers L.)

Abstract

Influence of different concentrations of cyanamide (0,1,2 and 3% a.i.) at different dates of pruning (5th October, 26th October and 16th November, 1989) on budbreak and the consequential effect of variation in budbreak on different dates shoot growth, bunch development and berry quality was studied in Thompson Seedless grape under the mild tropical climatic conditions of South interior Karnataka. Budbreak at all nodal positions, except the terminal two nodes was influenced by the dates of pruning as well as the cyanamide concentration. Irrespective of the concentration, cyanamide treatment increased the budbreak, which in turn was associated with increased yield, brix-yield/cane and increase in the proportion of water berries. Cyanamide treatment hastened budbreak by about 6 days in vines pruned on 5th October and about 4 days in vines pruned on 26th October for 50% budbreak to occur. Vines pruned on 16th November and not treated with cyanamide did not show even 50% budbreak. Mean shoot length was reduced by delayed pruning and cyanamide treatment. Total shoot length/cane decreased with delay pruning but was unaffected by cyanamide treatments. Reduced total shoot length/cane was associated with reduced yield and brix-yield/cane and mean bunch and berry weights. Vines pruned on 5th October resulted in higher yield than those pruned later. Higher yield was mediated through higher weight of berries and bunch and increase in the number of clusters/cane. Cyanamide treatment did not increase the yield/cane. Proportion of water berries in a bunch decreased with delayed pruning. This however, was not affected by cyanamide treatment. Cyanamide treatment did not have any influence on the quality parameters. This study has thus shown that cyanamide can be used to hasten and increase budbreak in Thompson Seedless vines pruned as late as 16th November under the agroclimatic conditions of Bangalore. Cyanamide at 1% a.i. was found to be the optimum. For achieving increase in yield through budbreak by cyanamide, fruitfulness of buds on the cane should be improved.